threading

Starting a thread inside a finalizer works, but the new thread is a normal-priority foreground thread that resurrects the object, outlives GC.WaitForPendingFinalizers, can crash the process, and may touch objects that were already finalized. Blocking on it hangs shutdown. Eight cases reproduced on .NET 10 with real output, plus the safe handoff pattern.

A thread shares memory with every other thread in the process. A Dart isolate does not: it owns its heap, runs one event loop, and talks to other isolates only by messages. Here is what that means at the VM level, where isolate groups blur the line, and how it plays out in Flutter, FFI, and on the web.